Scoring circuit



June 3, 1958 F. w. BROWN 7 2,837,335

SCORING CIRCUIT Filed Jan. 9. 1956 l2 son XAAAIAQW J IMFD r [III] l8 uCOUNTER |4 METAL T0 40V METAL 0 SHORTING T i 6 TARGET GERMANIUM 5* moveme:

RELAY 8,000.0. ZMA

INVENTOR. V

FORREST W. BROWN AGENT.

United SCORING CIRCUIT Forrest W. Brown, New Canaan, Conn., assignor toThe Reflectone Corporation, Stamford, (loam, a corporation ofConnecticut Application January 9, 1956, Serial No. 558,044

' Claims. (01. 273-1192.

which indicates at a remote point the number of hits.

made on a target.

Targets which are adapted to sense the passage therethrough of a bulletand score upon such an occurrence are well known in the art. Suchtargets are usually made of two spaced, electrically insulatedelectrodes as described for instance in U. S. Patents, 474,109,2,576,960, and copending application for Letters Patent, Serial Numbers502,447 filed April 19, 1955 and 515,032 filed June 13, 1955. A bulletpassing through the target momentarily causes an electrical shortcircuit between the electrodes.

In connection with this type of target construction it is necessary toemploy electrical scoring means. Since the passing of a bullet throughthe target occurs in a minute fraction of a second, the actuation ofscoring relays, of counters and of other indicating means is difiicultsince mechanical devices cannot readily be actuated in such a shorttime. In view of this difiiculty electronic means are commonly usedwhich amplify the short signal received from the target and which inturn cause operation of the circuit components necessary for scoringindication.

The use of electronic components is made difficult and undesirable,primarily by the environmental conditions which usually prevail on opentarget ranges, particularly sand, dust, winds, ice, snow and rain andalso by the absence of suitable electrical energy which is necessary toenergize electronic amplifying devices. A source of 100 volts or betteris usually required to suitably energize electronic amplifying tubes, avoltage magnitude which is not readily available from storage batteries.Still further, the fragility of electronic tubes and the absence ofskilled maintenance personnel on firing ranges creates problems whichseriously impair the reliability of the entire target and scoringinstallation.

One of the objects of this invention is therefore to provide a new andimproved electrical scoring circuit which avoids one or more of thedisadvantages of prior art devices.

Another object of this invention is the provision of a scoring circuitcharacterized by utmost simplicity and reliability.

A still further object of this invention is the provision of anelectrical scoring circuit which avoids the use of electronic amplifyingmeans and eliminates the need for electronic vacuum tubes.

A still further object of this invention is the provision of anelectrical scoring circuit which will operate over a wide resistancevariation of the target.

Still another and further object of this invention is the provision of ascoring circuit which in view of the absence of thermionic tubesrequires but a minimum of standby power.

P ce

For a better understanding of the present invention together with otherand further objects thereof reference is made to the followingdescription taken in connection with the accompanying drawing in which:

The figure is a schematic circuit diagram of the target and scoringarrangement.

Referring now to numeral 11, a source of voltage is identified which viaa resistor 12 is connected to the electrodes 13 and 14 of a target.These electrodes preferably are electrically conductive electrodesspaced from one another and which momentarily are short-circuited uponthe passage of a bullet therethrough. Such targets are discussed ingreat detail in the references cited above. This target is connected inparallel with a scoring circuit which comprises the parallel combinationof a rectifier diode 15 and electrical relay 16, both of which areserially connected with a capacitor 17. The actuation of relay 16 causesthe energizing of an electrically operated indicating means, counter 18,which in its actuated position derives its power from the voltage source11.

The operation of this circuit may be visualized as follows:

When the target is in its normal condition, i. e electrodes 13 and 14insulated from one another, source 11 which for the purpose ofillustration is assumed to be 40 volts, is applied to the target. Alsocapacitor 17, asstuned to be 1 mfd. is charged to the supply voltage viaresistor 12, assumed to be 50 ohms. If due to rain, snow, or otherenvironmental condition a leakage exists across the target, that is aleakage resistance across electrodes 13 and 14, electrode 13 is stillmaintained at a positive voltage but its magnitude is reduced by thevoltage drop across the series resistor 12. The same applies forcapacitor 17.

Upon the passage of a bullet through the target, capacitor 17 dischargesthrough the pat h comprising electrode 13, electrode 14 and rectifier15. Since the short-circuit between electrodes 13 and 14 exists for afraction of a second only, it is important that rectifier 15 have a verylow forward resistance, so that the capacitor is substantiallydischarged during the time the target is shorted. It has been found thatthis can be achieved exceedingly well for instance by the use of agermanium diflused junction diode type 1N93 commercially available fromthe General Electric Company, Schenectady, New York. This rectifier ischaracterized by an extremely low forward resistance in the order of 10ohms under the conditions used, and by the ability of permitting thepassing of a high peak forward current.

After the bullet has passed through the target and the short circuit hasdisappeared capacitor 17 is slowly charged up to full voltage via thecircuit comprising resistor 12, capacitor 17 and relay 1d. The relay isis a relay of the type usually employed in anode circuits of vacuumtubes having for the purpose of illustration a rating of 8000 ohms and 2milliamperes. Vt/bile capacitor is being charged, current flows throughrelay 16 which actuates counter 18 to register a hit. The relayautomatically disconnects the counter 18 as soon as the current throughthe relay coil decreases to the drop-out value and shortly thereaftercapacitor 17 is fully charged so that the entire circuit is reset. Thecharging time of the capacitor is determined by the time constantcomprising the size of the capacitor and the resistance value of therelay coil and the series resistor. From the foregoing it will beapparent that the counter is actuated not while the bullet passesthrough the target but during the charge time of capacitor 17 thusobtaining a greater length of time. The diode employed in the circuitrequires no standby power, is extremely compact and as far as it isknown has a practically unlimited life. With the values as shown it hasbeen found that the resistance between electrodes 13 and 14 of thetarget may deteriorate from several thousand ohms to approximately 150ohms without impairing the operation and reliability of the circuit.

Although the above description and drawing states certain values for thecomponents used, it will be evident to those skilled in the art that thecomponents may be varied within wide limits without affecting theoperation and reliability of the circuit and that, the values stated areintended only for illustrative purposes.

While there has been described a certain preferred embodiment of theinvention it will be obvious to those skilled in the art that variouschanges and modifications may be made therein without departing from thefield of the invention which should be limited only by the scopeof theappended claims.

What is claimed is:

1. A scoring circuit fora target having a set of spaced electrodes whichbecome momentarily short-circuited by a bullet passing therethroughcomprising; a source of voltage connected to the electrodes of saidtarget rendering. one electrode of positive and the other electrode ofnegative potential; an electrical network including the winding of anelectrical relay and a rectifier in parallel and a capacitor connectedserially with said, rectifier and winding; said network connected inparallel with said target and said source thereby causing said capacitorto be maintained normally charged with electrical potential; saidrectifier connected so as to permit passage of current therethrough fromthe normally positive to the normally negative target electrode via saidcapacitor to cause said capacitor to discharge in response to the bulletestablishing a short circuit between said target electrodes; saidrectifier having a sufficiently low resistance in the direction ofcurrent fiow to cause substantial discharging of said capacitor duringthe momentary short circuit condition across said target electrodes;said relay having characteristics such that it Will not operate inresponse to discharge current, and an indicating device operated inresponse to the current flow through the coil of said relay when saidcapacitor is being restored to its charged condition.

2. A scoring circuit for a target having a set of spaced electrodeswhich become momentarily short-circuited by a bullet passingtherethrough comprising; a source of direct current voltage connected tothe electrodes of said target rendering one electrode of positive andthe other electrode of negative potential; an electrical networkincluding the winding of an electromagnetic relay and a solid staterectifier in parallel and a capacitor connected serially with saidrectifier and winding; said network connected in parallel with saidtarget and said source thereby causing said capacitor to be maintainednormally charged with electrical potential; said rectifier connected soas to permit passage of current therethrough from the normally positiveto the normally negative target electrode via said capacitor to causesaid capacitor to discharge in response to the bullet establishing ashort circuit between said target electrodes; said rectifier having asufiiciently low resistance in the direction of current flow to causesubstantial discharging of said capacitor during the momentary shortcircuit condition across said target electrodes; said relay havingcharacteristics such that it will not operate in response to dischargecurrent, and an indicating device operated in response to the currentfiow through the coil of said relay when said capacitor is beingrestored to its charged condition.

3, A scoring circuit as set forth in claim 2 wherein said rectifier is adiffused junction rectifier.

4. A scoring circuit as set forth in claim 2 wherein said indicatingdevice is a counter.

5. A scoring circuit for a target having a set of spaced metallicelectrodes which become momentarily shortcircuited by a bullet passingtherethrough comprising; a

source of direct current voltage connected via a. resistor to theelectrodes of said target rendering one electrode of positive and theother electrode of negative potential; an electrical network includingthe winding of an electromagnetic relay and a diode rectifier inparallel and a capacitor connected serially with said rectifier andwinding; said network connected in parallel with said target and saidsource thereby causing said capacitor to be maintained normally chargedwith electrical potential; said rectifier connected so as to permitpassage of current therethrough from the target electrodes viasaidcapacitor to cause said capacitor to discharge in response to thebullet establishing a short circuit between said target electrodes; saidrectifier having a sufficiently low resist ance in the direction ofcurrent flow to cause substantial discharging of said capacitor duringthe momentary short circuit condition across said target electrodes;said relay having characteristics such that it will not operate inresponse to discharge current, and an indicating device operated inresponse to the current flow through the coil of said relay when saidcapacitor is being restored to charged condition.

References Cited in the file of this patent UNITED STATES PATENTS2,080,273 Holmes May 1.1 1937 2,146,863 Stansbury Feb. 14-, 19392,347,481 Hooven Apr. 25, 1944. 2,749,123 Ream June 5,, 1956 2,749,124Ream June 5, 1956 2,749,125 Ream June 5, 1956

